Internal combustion engines with fuel injection systems, especially Diesel engines for powering motor vehicles, must often operate at various altitudes above sea-level, i.e., at variable atmospheric pressures. The injection pumps used with these engines are provided with regulators which have a quantitative full-load limitation, which is determined corresponding to the full-load or smoke limitation of the engine. In addition, these regulators are designed in many cases in such a way that the maximum quantity of fuel metered out in full-load operation can be changed over the largest possible range of rpms so that it adapts to the actual required power of the engine for smokeless combustion or for a special application. These regulators often include a correcting device for operation of the engine at very great altitudes. This device responds to the rarefied air at great heights, i.e., the lowered atmospheric pressure, and acts on the regulator in the sense of decreasing the fuel quantity injected by the fuel injection pump.
Thus, known fuel regulators of the above-described type for adaptation of the maximum quantity of fuel delivered by the fuel metering system to a changed atmospheric pressure have a correcting device, which contains a series of known diaphragm boxes and which is inserted into the linkage between the control rod and the intermediate lever of the regulator. The correcting device causes a change of position of the pin serving for the mounting of the intermediate lever depending on atmospheric pressure and thus causes a change of position of the fuel control rod. This known regulator has the disadvantage that the correcting device always carries out the same correction independently of the actual position of the adjusting member or of the control rod. Thus, both during engine idling and also in partial load operation, so much less fuel is injected that the engine will stop or will run irregularly, i.e., "buck".
Also known are governors for injection pumps which adapt the delivered fuel output to changing barometric pressure with a correcting device that engages an external lever on the control rod. A notched disc is disposed by diaphragm cells and serves as a fixed stop for the maximum deflection of the lever. This correcting device has the disadvantage of being able to carry out the necessary adjustment in height only in discrete steps. Furthermore, the position of the notched disc can be changed only whenever the lever is pulled away from the stop for deceleration, and, upon renewed acceleration, the lever will come to rest at the newly set stop position.
Further known are correcting devices which directly engage the control rod of the injection pump and limit its position thus determining the maximum fuel output. Such arrangements are disadvantageous whenever the regulators used with these injection pumps have an adapting arrangement which corrects the control sleeve path and thus the position of the control rod, so that the maximum fuel quantity for full load operation and a full load rpm is increased with decreasing rpm. The described correcting device which acts directly on the control rod only serves to decrease the maximum fuel quantity but does not take into consideration the adaptation to engine conditions so that too much fuel will be injected in the upper range of the rpm and the motor will smoke or will be overloaded.